This is the personalized info on the inside of a 1937 KM tunic. I've seen this red stitching & identical type of name tag on many other KM items. I'm pretty sure the letters and numbers are codes for the sailors unit id etc. Is this correct? Any help with these numbers would be very appreciated.

Hello, I have just seen this.

O - Ostsee naval station (N for the Nordsee station)
253 - Sailor number
38 - Year of incorporation of the sailor to the navy
T - Technical carrer specialist (S for seeman carrer specialist)
Label (Fakbender) - last name of the sailor

I hope this heps.